Method for treating surface of substrate

ABSTRACT

PCT No. PCT/JP96/02077 Sec. 371 Date May 14, 1997 Sec. 102(e) Date May 14, 1997 PCT Filed Jul. 25, 1996 PCT Pub. No. WO97/05228 PCT Pub. Date Feb. 13, 1997A method for treating the surface of a substrate with a surface treatment composition, wherein the surface treatment composition comprises a liquid medium containing a complexing agent as a metal deposition preventive.

TECHNICAL FIELD

The present invention relates to a surface treatment composition and amethod for treating the surface of a substrate using the same. Moreparticularly, the present invention relates to a surface treatmentcomposition comprising a liquid medium as the main component, whichprevents a substrate surface from being contaminated with metalimpurities from the surface treatment composition and stably provides anextremely clean substrate surface, and also relates to a method fortreating the surface of a substrate by using the same. Further, thepresent invention relates to a method for supplying components for thesurface treatment composition and a method for purifying a complexingagent used for the composition.

BACKGROUND ART

In accordance with high integration of various devices represented byVLSI, TFT liquid crystals and the like, cleanliness levels of substratesurfaces used for these devices are demanded to be higher and higher.Contaminations with various materials disturb to achieve highercleanliness, and among the contaminations, a metallic contaminationparticularly deteriorates electric properties of a device, and it istherefore necessary to utmostly lower a metal impurity concentration ona substrate surface for forming a device in order to prevent theabove-mentioned deterioration. For this purpose, it is generallyconducted to clean a substrate surface with a cleaning agent.

Heretofore, for this type cleaning agent, there are generally usedwater, electrolyzed ionic water, acid, alkali, oxidizing agent,surfactant aqueous solution or organic solvents and the like. Thecleaning agent is demanded not only to have excellent cleaningperformances but also to have an impurity concentration of such anextremely low level as to prevent a substrate from being contaminatedwith a metal impurity from the cleaning agent. In order to satisfy thesedemands, cleaning chemicals for semiconductors are highly purified, anda metal impurity concentration in the chemicals immediately afterpurification reaches a level of hardly detectable by present analyticaltechniques.

Although an impurity in a cleaning agent is lowered to such a low levelas to be hardly detectable, it is still difficult to provide a highlyclean substrate surface. This is because it can not be avoided that acleaning agent itself is contaminated with a metal impurity removed froma substrate in a cleaning tank. Thus, a metal impurity separated from ametal surface is incorporated into a cleaning agent and the metalimpurity in the contaminated cleaning agent is then deposited on asubstrate (reverse contamination).

In a step of cleaning semiconductors, cleaning (SC-1 cleaning) with"ammonia+hydrogen peroxide+water" solution is widely used (see RCAReview, p 187-206, June (1970) etc.). This cleaning is usually conductedat 40°-90° C., and the composition ratio of a cleaning solution usuallyused is (30 wt % aqueous ammonia):(31 wt % hydrogenperoxide):(water)=0.05:1:5 to 1:1:5. However, this cleaning method hashigh performances to efficiently remove particles and organic materials,but when metals such as Fe, Al, Zn and Ni are present even in a verysmall amount in the solution, they are deposited on a substrate surface,thus raising a problem of reverse contamination. For this purpose, inthe step of cleaning semiconductors, after cleaning with"ammonia+hydrogen peroxide+water" solution, cleaning with an acidcleaning agent such as "hydrochloric acid+hydrogen peroxide+water"solution (SC-2 cleaning) is usually conducted to remove metalcontamination on a substrate surface.

Therefore, in the cleaning step, a technique to prevent the reversecontamination has been demanded in order to stably and efficientlyprovide a highly clean surface.

Further, a problem of deposition of metal impurities in a liquid onto asubstrate surface is generally a large problem not only in the cleaningstep but also in substrate surface treatment steps using a solution suchas an alkali etching step of a silicon substrate, an etching step of asilicon oxide film with dilute hydrochloric acid, and the like. In theetching step with dilute hydrofluoric acid, when noble metal impuritiessuch as Cu and Au are present in the solution, they are deposited on thesilicon surface and extremely deteriorate electric properties of devicessuch as carrier lifetime. Although, in the alkali etching step, when asmall amount of metal impurities such as Fe and Al are present in thesolution, they are easily deposited on the substrate surface andadversely affect on its quality. Thus, a technique to preventcontamination in a surface treatment step with a solution is stronglydemanded.

In order to solve these problems, there is proposed a method forpreventing metal impurities from being deposited on a substrate surfaceby adding a complexing agent such as a chelating agent to a surfacetreatment agent to trap the metal impurities in the solution as stablewater-soluble complexes. For example, JP-A-50-158281 proposes to preventdeposition of metal impurities on a semiconductor substrate surface byadding a complexing agent such as ethylenediaminetetraacetic acid (EDTA)or ammonium cyanide to a tetraalkylammonium hydroxide aqueous solution.JP-A-3-219000 proposes a chelating agent such as catechol and Tiron,JP-A-5-275405 proposes a phosphonic acid type chelating agent or acomplexing agent such as condensed phosphoric acid and JP-A-6-163495proposes a complexing agent such as hydrazone derivative, and they arerespectively added to an alkaline cleaning solution such as"ammonia+hydrogen peroxide+water" solution to prevent metal impuritydeposition on a substrate, thereby providing a substrate surface notcontaminated with particles, organic materials and metals.

However, when these complexing agents are added, deposition of aspecific metal (such as Fe) can be prevented or a removal effect can berecognized, but there are problems that the effect of theabove-mentioned complexing agent is extremely small with regard tometals other than Fe (such as Al) which easily contaminate a treatingsolution or a substrate and that the effect can not be sufficientlyachieved even by adding a large amount of complexing agents. In order tosolvent these problems, JP-A-6-216098 proposes to clean a substrate with"ammonia+hydrogen peroxide+water" cleaning solution containing achelating agent such as a phosphonic acid type chelating agent and thento rinse with a hydrofluoric acid aqueous solution of at least 1 ppm.According to this method, since the cleaning solution containing thephosphonic acid type chelating agent does not substantially reduce Alcontamination on the substrate surface, Al is removed by etching withthe hydrofluoric acid aqueous solution of at least 1 ppm at the laterstep. Thus, the effect achieved by the conventional method forpreventing metal deposition is not satisfactory, and the metalcontamination must be removed at the later stage when the substrate isrequired to be cleaner. Consequently, the number of steps must beincreased, thereby making a production cost large.

Under these circumstances, various complexing agents have been tried tobe added in order to prevent a substrate surface from being contaminatedwith metal impurities from a surface treatment composition, but asatisfactory improvement can not be made and a satisfactory techniquefor preventing contamination can not be achieved up to now.

The present invention has been made to solve the above-mentionedproblems, and provides a surface treatment composition which prevents asubstrate surface from being contaminated with metal impurities from thesurface treatment composition and stably produces an extremely cleansubstrate surface, and also provides a method for treating the surfaceof a substrate by using the same.

DISCLOSURE OF THE INVENTION

According to the present invention, an effect of preventing a substratefrom being deposited with metal impurities from a surface treatmentcomposition is remarkably improved by incorporating specific at least 2complexing agents as a metal deposition preventive into the surfacetreatment composition.

Also, the present invention includes a surface treatment compositioncontaining only one kind of complexing agent which achieves an effect ofpreventing metal impurity deposition more satisfactorily than prior artswhen the metal deposition preventive to be contained in the surfacetreatment composition is a specific complexing agent.

Further, the present invention includes a method for efficientlysupplying lost components of a surface treatment composition whenconducting surface treatment with the surface treatment composition anda method for purifying ethylenediaminediorthohydroxyphenylacetic acid(hereinafter sometimes referred to as EDDHA) which is one of the mostsatisfactory metal deposition preventives.

Thus, the first essential feature of the present invention resides in amethod for treating the surface of a substrate with a surface treatmentcomposition, wherein the surface treatment composition comprises aliquid medium containing a complexing agent as a metal depositionpreventive, the complexing agent comprising at least one member selectedfrom the following Group A complexing agents and at least one memberselected from the group consisting of the following Groups B1 to B6complexing agents:

Group A: complexing agents having an aromatic hydrocarbon ring in themolecular structure thereof and at least one of an OH group and/or an O⁻group bonded directly to a carbon atom constituting the ring;

Group B1: complexing agents having at least one nitrogen atom as a donoratom in the molecular structure thereof;

Group B2: complexing agents having at least one atom selected fromhalogen, sulfur and carbon atoms as a donor atom in the molecularstructure thereof;

Group B3: complexing agents having at least one oxygen atom as a donoratom in the molecular structure thereof, but not having a carbonyl groupand a carboxyl group and not having any one of nitrogen, halogen, sulfurand carbon atoms as a donor atom;

Group B4: carboxylic acid type complexing agents having at least onecarboxyl group in the molecular structure thereof, but not having anyone of nitrogen, halogen, sulfur and carbon atoms as a donor atom andnot having a carbonyl group and a hydroxyl group;

Group B5: hydroxymono- or di-carboxylic acid type complexing agentshaving at most 4 hydroxyl groups in the molecular structure thereof, butnot having any one of nitrogen, halogen, sulfur and carbon atoms as adonor atom and not having a carbonyl group; and

Group B6: complexing agents having at least one carbonyl group in themolecular structure thereof.

The second essential feature of the present invention resides in amethod for treating the surface of a substrate with a surface treatmentcomposition which contains at least one complexing agent selected fromthe group consisting of ethylenediaminediorthohydroxyphenylacetic acidethylenediamine-N,N'-bis(orthohydroxyphenylacetic acid)!,2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonic acid,diammonium 4,4'-bis(3,4-dihydroxyphenylazo)-2,2'-stilbenedisulfonate,Pyrocatechol Violet, o,o'-dihydroxyazobenzene,1'2-dihydroxy-5-nitro-1,2'-azonaphthalene-4-sulfonic acid andN,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid as a metaldeposition preventive in a liquid medium.

Further, the third essential feature of the present invention resides ina method for treating the surface of a substrate with a surfacetreatment composition, wherein the surface treatment composition is acomposition containing an oxidizing agent and an organic complexingagent having an OH group bonded directly to an aromatic hydrocarbongroup in a liquid medium and the concentration of the oxidizing agent isfrom 1 ppm by weight to 3 wt %.

The fourth essential feature of the present invention resides in amethod for treating the surface of a substrate with an alkaline surfacetreatment composition containing ammonia, water and an organiccompleting agent having a cyclic structure in the molecular structurethereof and at least one of an OH group and/or an O⁻ group bonded to acarbon atom constituting the cyclic structure as a metal depositionpreventive in a liquid medium, wherein an ammonia component evaporatedduring the surface treatment is supplied with an ammonia aqueoussolution containing the organic complexing agent.

The fifth essential feature of the present invention resides in a methodfor treating the surface of a substrate with a surface treatmentcomposition, wherein the surface treatment composition is a compositionobtained by adding highly pureethylnenediaminediorthohydroxyphenylacetic acid containing at most 5 ppmof at least one metal element of Fe, Al and Zn or its ammonium salt, asa metal deposition preventive to a liquid medium, and a method forpurifying the highly pure ethylenediaminediorthohydroxyphenylacetic acidor its ammonium salt.

Hereinafter, the present invention is further described in more details.

The surface treatment composition used in the above-mentioned firstinvention is characterized by containing specific at least 2 complexingagents as a metal deposition preventive. The specific at least 2complexing agents comprise at least one complexing agent selected fromthe following Group A and at least one complexing agent selected fromthe group consisting of the following Groups B1, B2, B3, B4, B5 and B6.

In the present invention, the surface treatment generally refers tocleaning, etching, polishing and coating of a substrate, and the surfacetreatment composition generally refers to a surface treating agent usedfor these purposes.

Group A complexing agents have an aromatic hydrocarbon ring in themolecular structure thereof and at least one of an OH group and/or an O⁻group bonded to a carbon atom constituting the ring. Examples of thesecomplexing agents are illustrated below, but are not limited thereto.Also, examples are illustrated by a compound having an OH group, butinclude its corresponding salt such as an ammonium salt and an alkalimetal salt. Names in parenthesis ! after compound names refer toabbreviation or common names used in the present specification.

(A-1) Phenols having only one OH group and their derivatives

Phenol, cresol, ethylphenol, t-butylphenol, methoxyphenol, salicylalcohol, chlorophenol, aminophenol, aminocresol, amidol,p-(2-aminoethyl)phenol, salicylic acid, o-salicylanilide, naphthol,naphtholsulfonic acid, 7-amino-4-hydroxy-2-naphthalendisulfonic acid,and the like.

(A-2) Phenols having at least 2 OH groups and their derivatives

Catechol, resorcinol, hydroquinone, 4-methylpyrocatechol,2-methylhydroquinone, pyrogallol, 1,2,5-benzenetriol,1,3,5-benzenetriol, 2-methylfluoroglucinol,2,4,6-trimethylfluoroglucinol, 1,2,3,5-benzenetetraol, benzenehexanol,Tiron, aminoresorcinol, 2,4-dihydroxybenzaldehyde,3,4-dihydroxybenzaldehyde, dihydroxyacetophenone, 3,4-dihydroxybenzoicacid, gallic acid, 2,3,4-trihydroxybenzoic acid,2,4-dihydroxy-6-methylbenzoic acid, naphthalenediol, naphthalenetriol,nitronaphthol, naphthalenetetraol, binaphthyldiol,4,5-dihydroxy-2,7-naphthalenedisulfonic acid,1,8-dihydroxy-3,6-naphthalenedisulfonic acid, 1,2,3-anthracenetriol,1,3,5-tris((2,3-dihydroxybenzoyl)aminomethyl)benzene MECAM!,1,5,10-tris(2,3-dihydroxybenzoyl)-1,5,10-triazadecane 3,4-LICAM!,1,5,9-tris(2,3-dihydroxybenzoyl)-1,5,9cyclotriazatridecane 3,3,4-CYCAM!,1,3,5-tris((2,3-dihydroxybenzoyl)carbamide)benzene TRIMCAM!,entecrobactin, enancycloenterobactin and the like.

(A-3) Hydroxybenzophenones

Dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone,2,6-dihydroxy-4-methoxybenzophenone, 2,2',5,6'-tetrahydroxybenzophenone,2,3',4,4',6-pentahydroxybenzophenone, and the like.

(A-4) Hydroxybenzanilides

o-hydroxybenzanilide, and the like.

(A-5) Hydroxyanils

Glyoxalbis(2-hydroxyanil), and the like.

(A-6) Hydroxyphenyls

Biphenyltetraol, and the like.

(A-7) Hydroxyquinones and their derivatives

2,3-dihydroxy-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone,dihydroxyanthraquinone,1,2-dihydroxy-3-(aminomethyl)anthraquinone-N,N'-diacetic acid Alizarinecomplexane!, trihydroxyanthraquinone, and the like.

(A-8) Diphenyl- or triphenyl-alkane derivatives

Diphenylmethane-2,2'-diol, 4,4',4"-triphenylmethanetriol,4,4'-dihydroxyfuchsone, 4,4'-dihydroxy-3-methylfuchsone, PyrocatecholViolet PV!, and the like.

(A-9) Phenol derivatives of alkylamines

Ethylenediaminediorthohydroxyphenylacetic acid EDDHA!,N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid HBED!,ethylenediaminedihydroxymethylphenylacetic acid EDDHMA!, and the like.

(A-10) Phenol derivatives of alkylethers

3,3'-ethylenedioxydiphenol, and the like.

(A-11) Phenols having an azo group and their derivatives

Diammonium 4,4'-bis(3,4-dihydroxyphenylazo)-2,2'-stilbenedisulfonateStilbazo!,2,8-dihydroxy-1-(8-hydroxy-3,6-disulfo-1-naphthylazo)-3,6-naphthalenedisulfonicacid, o,o'-dihydroxyazobenzene,2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonic acidcalmasite!, chlorohydroxyphenylazonaphthol,1'2-dihydroxy-6-nitro-1,2'-azonaphthalene-4-sulfonic acid EriochromeBlack T!,2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3,6-naphthalenedisulfonicacid, 5-chloro-2-hydroxy-3-(2,4-dihydroxyphenylazo)benzene sulfonic acidLumogalion!, 2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3-naphthalicacid NN!, 1,8-dihydroxy-2-(4-sulfophenylazo)-3,6-naphthalenedisulfonicacid,1,8-dihydroxy-2,7-bi(5-chloro-2-hydroxy-3-sulfophenylazo)-3,6-naphthalenedisulfonicacid, 1,8-dihydroxy-2,7-bis(2-sulfophenylazo)-3,6-naphthalenedisulfonicacid, 2-3-(2,4-dimethylphenylaminocarboxy)-2-hydroxy-1-naphthylazo!-3-hydroxybenzenesulfonic acid, 2-3-(2,4-dimethylphenylaminocarboxy)-2-hydroxy-1-naphthylazo!phenol, andthe like.

In the first invention, at least one complexing agent selected from theabove Group A is contained as a metal deposition preventive. Acomplexing agent is selected by synthetically considering a cleaninglevel, a complexing agent cost, a chemical stability in a surfacetreatment composition and the like required for a substrate surface, andit is hard to say unconditionally which complexing agent is best.However, in respect of a metal deposition preventive effect, when thecontent of a complexing agent in a surface treatment composition isconstant, phenol derivatives of alkylamines such asethylenediaminediorthohydroxyphenylacetic acid EDDHA! and phenols havingat least 2 OH groups and their derivatives such as catechol and Tironare excellent and are preferably used. Also, in respect of chemicalstability, phenol derivatives of alkylamines such asethylenediaminediorthohydroxyphenylacetic acid EDDHA! are excellent, andin respect of a production cost of a complexing agent, 8-quinolinol,catechol, Tiron and the like are excellent and are preferably used whenthese factors are considered important. Further, a complexing agenthaving not only an OH group but also a sulfonic acid group and acarboxyl group, is excellent and preferable in respect of a metaldeposition preventive effect and a chemical stability.

Examples of other complexing agents used in combination with acomplexing agent of Group A, include complexing agents of the followingGroups B1 to B6. (Group B1) Complexing agents having at least onenitrogen atom as a donor atom in the molecular structure thereof. (GroupB2) Complexing agents having at least one atom selected from halogen,sulfur and carbon atoms as a donor atom in the molecular structurethereof. (Group B3) Complexing agents having at least one oxygen atom asa donor atom in the molecular structure thereof, but not having acarbonyl group and a carboxyl group and not having any one of nitrogen,halogen, sulfur and carbon atoms as a donor atom. (Group B4) Carboxylicacid type complexing agents having at least one carboxyl group in themolecular structure thereof, but not having any one of nitrogen,halogen, sulfur and carbon atoms as a donor atom and not having acarbonyl group and a hydroxyl group. (Group B5) Hydroxymono- ordi-carboxylic acid type complexing agents having at most 4 hydroxylgroups in the molecular structure thereof, but not having any one ofnitrogen, halogen, sulfur and carbon atoms as a donor atom and nothaving a carbonyl group. (Group B6) Complexing agents having at leastone carbonyl group in the molecular structure thereof.

In the present invention, a donor atom means an atom which can provideelectrons necessary for a coordinate bond with a metal. Examples of acoordinate group having a nitrogen atom as a donor atom in the Group B1,include an amino group, an imino group, a nitrilo group (tertiarynitrogen atom), a thiocyanate group, a hydroxyamino group, ahydroxyimino group, a nitro group, a nitroso group, a hydrazino group, ahydrazono group, a hydrazo group, an azo group, an azoxy group, adiazonium group and an azide group. Examples of complexing agents havingthese coordinate groups are illustrated below, but are not especiallylimited thereto.

(B1- 1) Monoamines

Ethylamine, isopropylamine, vinylamine, diethylamine, dipropylamine,N-methylethylamine, triethylamine, benzylamine, aniline, toluidine,ethylaniline, xylidine, thymylamine, 2,4,6-trimethylaniline,diphenylamine, N-methyldiphenylamine, biphenylylamine, benzidine,chloroaniline, nitrosoaniline, aminobenzenesulfonic acid, aminobenzoicacid, and the like.

(B1- 2) Diamines and polyamines

Ethylenediamine, propylenediamine, trimethylenediamine,hexamethylenediamine, diethylenetriamine, diaminobenzene,toluenediamine, N-methylphenylenediamine, triaminobenzene,aminodiphenylamine, diaminophenylamine, and the like.

(B1- 3) Amino alcohols

Ethanol amine, 2-amino-1-butanol, 2-amino-2-methyl-1-propanol,2-amino-2-ethyl-1,3-propanediol, 2-(ethylamino)ethanol,2,2'-iminodiethanol, dimethylethanolamine, diethylethanolamine,ethyldiethanolamine, 3-diethylamino-1,2-propanediol, triethanolamine,and the like.

(B1-4) Aminophenols

Aminophenol, p-aminophenol sulfate, (methylamino)phenol,aminoresorcinol, and the like.

(B1- 5) Amino acids

Glycine, glycineethylester, sarcosine, alanine, aminobutyric acid,norvaline, valine, isovaline, norleucine, leucine, isoleucine, serine,L-threonine, cysteine, cystine, methionine, ornithine, lysine, arginine,citrulline, asparagic acid, asparagine, glutamic acid, glutamine,β-hydroxyglutamic acid, N-acetylglycine, glycylglycine, diglycylglycine,phenylalanine, tyrosine, L-thyroxine, N-phenylglycine, N-benzoylglycine,and the like.

(B1-6) Iminocarboxylic acids

Iminodiacetic acid, nitrilotriacetic acid, nitrilotripropionic acid,ethylenediaminediacetic acid EDDA!, ethylenediaminetetraacetic acidEDTA!, hydroxyethylethylenediaminetetraacetic acid EDTA-OH!,trans-1,2-diaminocyclohexanetetraacetic acid CyDTA!,dihydroxyethylglycine DHGE!, diaminopropanoltetraacetic acid DPTA-OH!,diethylenetriaminepentaacetic acid DTPA!,ethylenediaminedipropiondiacetic acid EDDP!, glycol etherdiaminetetraacetic acid GEDTA!, 1,6-hexamethylenediaminetetraacetic acidHDTA!, hydroxyethyliminodiacetic acid HIDA!, methylEDTA(diaminopropanetetraacetic acid), triethylenetetraminehexaacetic acidTTHA!, 3,3'-dimethoxybenzidine-N,N,N'N'-tetraacetic acid, and the like.

(B1-7) Iminophosphonic acids

Ethylenediamine-N,N'-bis(methylenephosphonic acid) EDDPO!,ethylenediaminetetrakis(methylenephosphonic acid) EDTPO!,nitrilotris(methylenephosphonic acid) NTPO!,diethylenetriaminepenta(methylenephosphonic acid) ETTPO!,propylenediaminetetra(methylenephosphonic acid) PDTMP! and the like.

(B1-8) Heterocyclic amines

Pyridines such as pyridine, conyrine, lutidine, picoline, 3-pyridinol,isonicotinic acid, picolinic acid, acetylpyridine, nitropyridine,4-pyridone, bipyridyl, 2,4,6-tris(2-pyridyl)-1,3,5-triazine TPTZ!,3-(2-pyridyl)-5,6-bis(4-sulfonyl)-1,2,4-triazine PDTS!,synphenyl-2-pyridylketoxime PPKS!, and the like; quinolines such asquinoline, quinaldine, lepidine, dimethylquinoline, 8-quinolinol,2-methyl-8-quinolinol, methoxyquinoline, chloroquinoline, quinolinediol,quinaldinic acid, quinic acid, nitroquinoline, kynurine, kynurenic acid,8-acetoxyquinoline, bicinchonic acid, and the like; isoquinolines;benzoquinolines such as acridine, 9-acridone, phenanthridine,benzoquinoline, benzoisoquinoline, and the like; naphthoquinolines suchas naphthoquinoline and the like; and phenanthrolines such aso-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, basocuproin,basocuproin sulfonic acid, basophenonethroline,basophenanthrolinesulfonic acid,2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and the like.

Further, pyrazoles such as pyrazole, 5-pyrazolone, and the like;imidazoles such as imidazole, methylimidazole, and the like;imidazolines and imidazolidines such as 2-imidazoline, imidazolidine,ethyleneurea, and the like; benzoimidazoles such as benzoimidazole andthe like; diazines such as diazine, pyrimidine, pyrazine, and the like;hydropyrimidines such as uracyl, thymine, and the like; piperazines suchas piperazine, and the like; benzodiazines and dibenzodiazines such ascinnoline, phenazine, and the like; triazines; purines; oxazoles andisooxazoles such as oxazole, 4-oxazolone, isooxazole, azoxime and thelike; oxazines such as 4H-1,4-oxazine, morpholine, and the like;thiazoles and benzothiazoles; isothiazoles; thiazines; pyrroles;pyrrolines and pyrrolidines; indoles, indolines; isoindoles; carbazoles;inindigos; porphyrins; and the like.

(B1-9) Amides and imides

Carbamic acid, ammonium carbamate, oxamic acid, ethyl oxamate, ethylN-nitrocarbamate, carbanilic acid, carbonylonitrile, oxanylic acid,formamide, diacetamide, hexaneamide, acrylamide, lactic acid amide,cyanoacetamide, oxamide, succinamide, salicylamide, nitrobenzamide,succinimide, maleimide, phthalic imide, and the like.

(B1-10) Anilides

Formanilides, acetanilide, hydroxyanilide, chloroanilide,methoxyacetanilide, oxanilide, and the like.

(B1-11) Urea, thiourea and its derivatives

Urea, N-methyl urea, N,N'-ethylidene urea, allophanic acid, glycoluricacid, oxaluric acid, buret, N-nitro urea, azodicarboneamide, thiourea,methylthiourea, dimethylthiourea, and the like.

(B1-12) Oximes

Formaldoxime, p-benzoquinonedioxime, benzaldoxime, benzyldioxime, andthe like.

(B1-13) Compounds containing a coordinate group having nitrogen atomsbonded to each other

As hydrazines and hydrazides of azobenzene, azotoluene, Methyl Red,azobenzene dicarboxylic acid, hydroxyazobenzene, azoxybenzene and thelike: azo and azoxy compounds including phenylhydrazine,p-bromophenylhydrazine, p-nitrophenylhydrazine, N',-phenylacetohydrazideand the like; hyrazo compounds including hydrazobenzene,hydrazodibenzoic acid and the like; hydrazones including oxalicbis(salicylidenehydrazide), salicylaldehyde (2-carboxyphenyl)hydrazone,benzaldehyde hydrazone, acetaldehydephenylhydrazone and the like; azinesincluding benzylideneazine and the like; azides including benzoylazideand the like; diazonium salts including benzene diazonium chloride andthe like; diazo compounds including benzenediazohydroxide and the like;semicarbazides including semicarbazide and the like; andthiosemicarbazides including thiosemicarbazide and the like.

(B1-14) Others

Azides such as ammonium azide, sodium azide and the like; nitriles suchas acetonitrile and the like; amidosulfuric acid, imidodisulfuric acid,nitridetrisulfuric acid, thiocyanic acid, ammonium thiocyanate, and thelike.

In respect to a metal deposition preventive effect, when a content of acomplexing agent in a surface treatment composition is constant, amongthe above Group B1, particularly amino acids such as glycine,iminocarboxylic acids such as iminodiacetic acid, nitrilotriacetic acidand ethylenediaminetetraacetic acid EDTA!, and heterocyclicpolycycloamines such as 8-quinolinol and o-phenanthroline, are excellentand preferably used.

Complexing agents of Group B2 include complexing agents having at leastone atom selected from halogen, sulfur and carbon atoms as a donor atomin the molecular structure thereof. Examples of these complexing agentshaving such a donor atom are illustrated below, but are not especiallylimited thereto. Also, salts of the following illustrated complexingagents include alkali metal salts or ammonium salts.

(B2-1) Complexing agents having a halogen atom as a donor atom

Hydrofluoric acid or its salt, hydrochloric acid or its salt, hydrogenbromide or its salt, hydrogen iodide or its salt.

(B2-2) Complexing agents having a sulfur atom as a donor atom

Compounds selected from thiol, sulfide or thiocarbonyl compoundsexpressed by RSH, R'₂ S or R₂ C═S or having at least one coordinategroup expressed by the formula HS⁻, S²⁻, S₂ O₃ ²⁻, RS⁻, R-COS⁻, R-CSS⁻or CS₃ ²⁻. In the above formulas, R is an alkyl group, and R' is analkyl group or an alkenyl group, and they may be bonded to form a ringcontaining a sulfur atom. Examples of these compounds include compoundshaving a HS⁻ group or a S²⁻ group such as hydrogen sulfide or its salt,or sulfides including sodium sulfide, ammonium sulfide and the like;compounds having a S₂ O₃ ²⁻ group such as thiosulfuric acid or its salt;compounds having a RSH or RS⁻ group such as lower alkylthiol includingthiol, ethanethiol and 1-propanethiol or their salts; compounds having aR-COS⁻ group such as thioacetic acid, dithiooxalic acid or their salts;compounds having a R-CSS⁻ group such as ethanedibis(dithio acid),dithioacetic acid or their salts; compounds having a CS₃ ²⁻ group suchas trithiocarbonic acid or their salts or thiocarbonic acid estersincluding diethyl trithiocarbonate and the like; sulfides expressed byR'₂ S such as methylsulfide, methylthioethane, diethylsulfide, vinylsulfide, benzothiophene and the like; and thiocarbonyl compoundsexpressed by R₂ C═S group such as propanethion, 2,4-pentanedion and thelike.

(B2-3) Complexing agents having a carbon atom as a donor atom

Examples of these compounds include compounds having a NC⁻, RNC or RCC⁻group as a coordinate group. Particular examples include cyanides suchas hydrogen cyanide and ammonium cyanide, isocyanides such as ethylisocyanide, allylene, metal acetylide and the like.

Among the above Group B2, a complexing agent having halogen as a donoratom such as hydrofluoric acid and hydrochloric acid, are excellent inrespect to both metal deposition preventive effect and cost, and arepreferably used.

Complexing agents of Group B3 include complexing agents having at leastone oxygen atom as a donor atom in the molecular structure thereof, butnot having a carbonyl group and a carboxyl group and not having any onenitrogen, halogen, sulfur and carbon atoms as a donor atom. Examples ofthese complexing agents are illustrated below, but are not especiallylimited thereto. The following illustrated acids such as sulfonic acidand oxo acid are described as an acid, but their salts such as alkalimetal salts or ammonium salts are included therein.

(B3-1) Complexing agents having a hydroxyl group

Saturated alcohols such as methanol, ethanol, propanol, isopropylalcohol, butanol, pentanol, hexanol, benzyl alcohol and the like;unsaturated alcohols such as allyl alcohol, methyl vinyl carbinol andthe like; polyhydric alcohols such as ethylene glycol, glycerine and thelike; phenols such as phenol, catechol, Tiron and the like; and theirderivatives.

(B3-2) Complexing agents having a phosphoric acid group

Benzene phosphonic acid and the like.

(B3-3) Complexing agents having a sulfonic acid group

Aliphatic sulfonic acids such as methanesulfonic acid and ethanesulfonicacid; and aromaticsulfonic acids such as benzenesulfonic acid,dodecylbenzenesulfonic acid and naphthalenesulfonic acid.

(B3-4) Complexing agents having an ether group

Dimethoxymethane, 1,4-dioxane, and the like.

(B3-5) Oxo acids

Suluric acid, phosphoric acid, condensed phosphoric acid, boric acid,silicic acid, carbonic acid, nitric acid, nitrous acid, perchloric acid,chloric acid, chlorous acid, hypochlorous acid, and the like.

(B3-6) Acid esters

Sulfuric acid esters such as ethylsulforic acid, dimethylsulforic acidand the like, carbonic acid esters such as dimethyl carbonate, diphenylcarbonate and the like, phosphoric acid esters such as trimethylphosphate, triphenyl phosphate and the like, trimethyl borate, ethylnitrate, ethyl nitride, and the like.

Among the above Group B3, particularly, aliphatic alcohols such asisopropyl alcohol and oxo acids such as phosphoric acid and nitrous acidare excellent and preferably used in respect to both metal depositionpreventive effect and cost.

Complexing agents of B4 Group are carboxylic acid type complexing agentshaving at least one carbonyl group in the molecular structure thereof,but not having any one of nitrogen, halogen, sulfur and carbon atoms asa donor atom and not having a carbonyl group and a hydroxyl group.Examples of Group B4 complexing agents are illustrated below, but arenot especially limited thereto. Also, carboxylic acids are illustratedas a free acids, but their salts such as ammonium salts and alkali metalsalts are included therein.

(B4-1) Monocarboxylic acids

Formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid,valeric acid, decanoic acid, undecanoic acid, dodecanoic acid, stearicacid, acrylic acid, crotonic acid, oleic acid, monochloroacetic acid,dichloroacetic acid, trichloroacetic acid, fluoroacetic acid, benzoicacid, methylbenzoic acid, chlorobenzoic acid, sulfocarboxylic acid,phenylacetic acid, and the like.

(B4-2) Polycarboxylic acid,

Oxalic acid, malonic acid, uccinic acid, maleic acid, fumaric acid,1,2,3-propanetricarboxylic acid, chlorosuccinic acid, phthalic acid,1,3,5-benzenetricarboxylic acid, dichlorophthalic acid, phenylsuccinicacid, and the like.

Among the above Group B4, particularly, carboxylic acids having arelatively simple structure, i.e. C₂ -C₃ aliphatic saturated carboxylicacids such as acetic acid and oxalic acid are excellent and preferablyused in respect to both metal deposition preventive effect and cost.

Complexing agents Group B5 are hydroxymono- or di-carboxylic acid typecomplexing agents having at most 4 hydroxyl groups in the molecularstructure thereof, but not having any one of nitrogen, halogen, sulfurand carbon atoms as a donor atom and not having a carbonyl group. In thepresent invention, a donor atom means an atom which can provideelectrons necessary for a coordinate bond with a metal. Examples ofGroup B complexing agents are illustrated below, but are not especiallylimited thereto. The following hydroxycarboxylic acids are illustratedas a free acid, but their ammonium salts, alkali metal salts and thelike are included therein.

(B5-1) Hydroxymonocarboxylic acids having at most 4 hydroxyl groups

Hydroxymonocarboxylic acids having one hydroxyl group such as glycolicacid, lactic acid, 2-hydroxybutyric acid, hydroacrylic acid,hydroxybenzoic acid, salicylic acid, sulfosalicylic acid and the like,hydroxymonocarboxylic acids having two hydroxyl groups such as glycericacid, 8,9-dihydroxystearic acid, 2,4-dihydroxybenzoic acid,protecatechuic acid and the like, and hydroxymonocarboxylic acids havingthree hydroxyl groups such as gallic acid and the like.

(B5-2) Hydroxydicarboxylic acids having at most 4 hydroxyl groups

Hydroxydicarboxylic acids having one hydroxyl group such as tartronicacid, malic acid, 2-hydroxybutanediacetic acid,2-hydroxydodecanediacetic acid, hydroxyphthalic acid and the like,hydroxydicarboxylic acids having two hydroxyl groups such as tartaricacid, 3,4-dihydroxyphthalic acid and the like, and hydroxydicarboxylicacids having four hydroxyl groups such as tetrahydroxysuccinic acid andthe like.

Among the above Group B5, particularly, hydroxydicarboxylic acids orhydroxymonocarboxylic acids having at most 2 hydroxyl groups, such astartaric acid salicylic acid, sulfosalicylic acid and the like areexcellent and preferably used in respect to metal deposition preventiveeffect, chemical stability and cost.

On the other hand, hydroxycarboxylic acids having at least 3 carboxylgroups such as citric acid do not achieve a satisfactorily metaldeposition preventive effect, and hydroxycarboxylic acids having atleast 5 hydroxyl groups such as gluconic acid, galactonic acid and thelike are not preferable since they are generally poor in chemicalstability and do not achieve a stable metal deposition preventiveeffect.

Further, a metal deposition preventive effect is related to thepositions of a hydroxyl group and a carboxyl group in a molecule and itis preferable that he two groups are bonded to carbon atoms closelypositioned.

Complexing agents of Group B6 include complexing agents having at leastone carbonyl group in the molecular structure thereof, but not havingany one of nitrogen, halogen, sulfur and carbon atoms as a donor atom inthe molecular structure thereof. Examples of these complexing agents inthe present invention are illustrated below, but are not especiallylimited thereto.

(B6-1) Aliphatic aldehydes

Formaldehyde, acetaldehyde, propionaldehyde, isobutylaldehyde,acrylaldehyde, crotonaldehyde, chloroacetaldehyde, dichloroacetaldehyde,butylchloral, hydroxyacetaldehyde, lactaldehyde, D-glycerinaldehyde,formal, acetal, dichloroacetal, and the like.

(B6-2) Aliphatic ketones

Acetone, ethyl methyl ketone, 2-methylpentanone, 3-pentanone,3-methyl-2-butanone, 4-methyl-2-pentanone, pinacolin, 2-heptanone,3-heptanone, 4-heptanone, 6-methyl-heptahnone, diisobutyl ketone,di-tert-butyl ketone, dihexyl ketone, methyl vinyl ketone, allylacetone,1-chloro-2-propanone, 1,1-dichloro-2-propanone, hydroxyacetone,dihydroxyacetone, and the like.

(B6-3) Polyoxo compounds

Di-, and poly-aldehydes such as glyoxal, malonaldehyde, succinealdehyde,and the like, di-, and poly-ketones such as diacetyl, acetylacetone,acetonylacetone, diacetylacetone, and the like, and ketoaldehydes suchas pyruvine aldehyde, 4-oxopentanal, and the like.

(B6-4) Ketenes

Ketene, dimethylketene, and the like.

(B6-5) Ketocarboxylic acids and aldehydecarboxylic acids

4,4,4-trifluoro-1-phenyl-1,3-butanedione,2,2,6,6-tetramethyl-3,5-heptanedione, pyruvic acid, malonealdehyde acid,acetacetic acid, glyoxlic acid, mesooxalic acid, oxalacetic acid,oxaloglutaric acid, and the like.

(B6-6) Aromatic aldehydes and aromatic ketones

Benzaldehyde, tolualdehyde, phenylacetaldehyde, cinnamaldehyde,terephthalaldehyde, protocatecaldehyde, acetophenone,methylacetophenone, benzophenone, chloroacetophenone,dihydroxybenzophenone, phenylglyoxal, and the like.

(B6-7) Quinones

o-benzoquinone, p-benzoquinone, naphthoquinone, quinhydrone,2,6-dichloro-p-benzoquinone, 2,5-dihydroxy-p-benzoquinone,tetrahydroxy-p-benzoquinone, 2,3-hydroxy-1,4-naphthoquinone, and thelike.

(B6-8) Tropolones

Tropolone, 6-isopropyltropolone, and the like.

The second invention of the present invention resides in that asatisfactory metal deposition preventive effect can be achieved even byonly one kind of completing agent when the completing agent to be addedto a liquid medium is ethylenediaminediorthohydroxyphenylacetic acidEDDHA!, 2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonicacid Carmagite!, diammonium4,4'-bis(3,4-dihydroxyphenylazo)-2,2'-stilbenedisulfonate Stilbazo!,Pyrocatechol Violet PV!, o,o'-dihydroxyazobenzene,1'2-dihydroxy-5-nitro-1,2'-azonaphthalene-4-sulfonic acid EriochromeBlack T! or N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acidHBED!.

An amount of a complexing agent to be added as a metal depositionpreventive can not be simply determined since the amount added isdepending on the kind and amount of a metal impurity in a liquid medium,the deposition of which is prevented, and a cleaning level demanded fora substrate surface, but the total amount to be added in a surfacetreatment composition is generally from 10⁻⁷ to 2 wt %, preferably from10⁻⁶ to 0.5 wt %, more preferably from 10⁻⁶ to 0.1 wt %. If the aboveamount is too small, the aimed metal deposition preventive effect of thepresent invention is hardly achieved. On the other hand, if the aboveamount is too large, the aimed effect can not be achieved any furtherand there is a fear that the complexing agent as a metal depositionpreventive tends to be unfavorably deposited on a substrate surface.

Examples of a liquid medium used as the main component for a surfacetreatment composition of the present invention include generally water,electrolyzed ionic water, an organic solvent or an aqueous solutionhaving an acid, an alkali, an oxidizing agent, a reducing agent, asurfactant or the like dissolved, or their mixture solutions.Particularly when an alkaline aqueous solution or a dilute hydrofluoricacid solution is used for cleaning or etching a semiconductor substrate,metal impurities in the solution are very easily deposited on asubstrate surface, and therefore in such cases, it is preferable to usethese solutions by adding a complexing agent in accordance with thepresent invention.

In the present invention, the alkaline aqueous solution means generallyan aqueous solution having a pH value of higher than 7. Examples of analkaline component in this aqueous solution are not especially limited,but typically include ammonia. Also, other usable examples includealkali metal or alkali earth metal hydroxides such as sodium hydroxide,potassium hydroxide and calcium hydroxide, alkaline salts such as sodiumhydrogen carbonate and ammonium hydrogen carbonate, or quaternaryammonium salt hydroxides such as tetramethylammonium hydroxide (TMAM),trimethyl-2-hydroxyethylammonium hydroxide and choline, and the like.These alkalis may be added in a mixture of two or more, and the totalconcentration of the total solution of surface treatment composition isadjusted to from 0.01 to 30 wt %. Also, alkali electrolyzed ionic waterobtained by electrolysis of water is preferably used. Further, to suchan alkaline aqueous solution, an oxidizing agent such as hydrogenperoxide may be optionally added. In a cleaning step of semiconductorwafer, when cleaning bare silicon (having no oxidized film), it ispossible to control etching or surface-roughening of the wafer byincorporating an oxidizing agent. When hydrogen peroxide is incorporatedinto the alkaline aqueous solution of the present invention, thehydrogen peroxide concentration in the total solution of surfacetreatment composition is generally adjusted within the concentrationrange of from 0.01 to 30 wt %. When an oxidizing agent is used, theoxidizing agent concentration is preferably adjusted to from 1 ppm byweight to 3 wt %. If the amount of the oxidizing agent is too large, acomplexing agent is decomposed, and the stability of the surfacetreatment composition tends to become poor. Particularly, when hydrogenperoxide is used as the oxidizing agent, the hydrogen peroxideconcentration is preferably from 100 ppm by weight to 3 wt %.

Method for blending the complexing agent of the present invention with asurface treatment composition is not especially limited. The complexingagent may be blended previously with one component or plural componentsof the components constituting a surface treatment composition (such asaqueous ammonia, hydrogen peroxide, water and the like), and then thesecomponents may be mixed. Alternatively, the complexing agent may beblended with a mixture solution obtained after mixing the components.Also, when acids such as phenols, amino acids, iminocarboxylic acids andthe like, are added, these acids may be added in the form of an acid orthey may be added in the form of a salt such as an ammonium salt.

In the case of SC-1 cleaning, surface treatment is carried out with acomposition of (ammonia+hydrogen peroxide+water+metal depositionpreventive), but when the surface treatment composition is used for along time, ammonia is evaporated and the metal deposition preventive isgradually decomposed, thereby degrading the metal deposition preventiveeffect. Therefore, when the evaporated ammonia content is supplied, thesupplement is conducted preferably with an aqueous ammonia containing ametal deposition preventive in an amount of from 10⁻⁷ to 5 wt %,preferably from 10⁻⁶ to 1 wt %.

The surface treatment composition of the present invention is used forsurface treatment operations including cleaning, etching, polishing,film-forming and the like, for substrates such as semiconductor, metal,glass, ceramics, plastic, magnetic material, superconductor and thelike, the metal impurity contamination of which becomes troublesome. Thepresent invention is preferably applied particularly to cleaning oretching of a semiconductor substrate, the surface of which is demandedto be highly clean. Among the cleaning operations of semiconductorsubstrate, when the present invention is applied particularly to alkalicleaning with a cleaning solution comprising (ammonia+hydrogenperoxide+water), the problem of said cleaning method, i.e. the problemof metal impurity deposition on a substrate can be solved, and by thiscleaning, there can be satisfactorily provided a highly clean substratesurface without being contaminated with particles, organic materials andmetals.

The reason why the surface treatment composition of the presentinvention achieves a very satisfactory effect of preventing depositionof metal impurities, is not clear up to now, but it is considered thatsome mixing effect is achieved and some stable water-soluble metalcomplex is effectively formed between metal ions and specific two ormore complexing agents added.

When the surface treatment composition of the present invention is usedas a cleaning solution for cleaning a substrate, a method of bringingthe cleaning solution directly into contact with the substrate isemployed. Examples of such a cleaning method include dipping typecleaning wherein a substrate is dipped in the cleaning solution in acleaning tank, spraying type cleaning wherein the cleaning solution issprayed on a substrate, spinning type cleaning wherein the cleaningsolution is dropped on a substrate rotated at a high speed, and thelike. In the present invention, among the above-mentioned cleaningmethods, a suitable method is employed depending on an object, but thedipping type cleaning method is preferable. The cleaning is carried outfor a suitable time, preferably from 10 seconds to 30 minutes, morepreferably from 30 seconds to 15 minutes. If the cleaning time is tooshort, the cleaning effect is not satisfactory. On the other hand, ifthe cleaning time is too long, it is meaningless since the throughputbecomes poor and the cleaning effect is not raised any further. Thecleaning may be carried out at normal temperature, but may be carriedout at a heated temperature to improve the cleaning effect. Also, thecleaning may be carried out in combination with a cleaning methodemploying a physical force. Examples of the cleaning method employing aphysical force include ultrasonic cleaning, mechanical cleaningemploying a cleaning brush, and the like.

In the present invention, in the preparation of a surface treatmentcomposition, a complexing agent sometimes becomes a metal contaminationsource. An ordinary reagent for the complexing agent contains metalimpurities such as Fe in an amount of from several to several thousandsppm. These metal impurities are present as a stable complex with thecomplexing agent at the initial stage, but when the complexing agent isused as a surface treatment solution for a long time, the complexingagent is decomposed and metals become free and are deposited on thesubstrate surface. Therefore, the content of at least one metal elementof Fe, Al and Zn in the complexing agent to be used is preferably atmost 5 ppm, and it is particularly preferable that the Fe content is atmost 5 ppm, the Al content is at most 2 ppm and the Zn content is atmost 2 ppm. In order to obtain such a complexing agent, when thecomplexing agent to be used is EDDHA, EDDHA is purified by dissolvingEDDHA or its salt in an acidic or alkaline solution, removing insolubleimpurities by filtration, precipitating a crystal of EDDHA byneutralization and finally separating the crystal from the solution.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is not limited to such specific Examples within the scope ofthe subject matter of the present invention.

EXAMPLES 1 TO 8 (use of single complexing agent) and COMPARATIVEEXAMPLES 1 TO 3

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 0.25:1:5, and to the aqueous solvent thusobtained, was added a predetermined amount of each complexing agentshown in the following Table 1 as a metal deposition preventive toprepare a surface treatment composition. The amount of the complexingagent added was expressed by wt %, and the name of the complexing agentwas expressed by the above-mentioned common name. Comparative Exampleswere prepared respectively by adding ethylenediamine tetrakis(methylsulfonic acid) (common name: EDTPO) disclosed in JP-A-5-275405 asa complexing agent; by adding oxalic bis(salicylidenehydrazide)disclosed in JP-A-6-163496 as a complexing agent; or by adding nocomplexing agent.

To each of the surface treatment solutions, was added 10 ppb of each ofAl and Fe (by using chlorides), and a clean silicon wafer (p type, CZ,plane orientation (100)) was dipped for 10 minutes in each of thesurface treatment solutions. During dipping, a liquid temperature ofeach surface treatment solution was raised and maintained at 40°-50° C.After dipping, each silicon wafer was overflow-rinsed with ultra-purewater for 10 minutes, and was dried with nitrogen blow to determine Aland Fe deposited on the wafer surface. Al and Fe deposited on thesilicon wafer were recovered with a mixture solution of 0.1 wt % ofhydrofluoric acid and 1 wt % of hydrogen peroxide, and the metal amountswere measured by flameless atomic absorption spectrometry and wereconverted into a substrate surface concentration (atoms/cm²). Theresults are shown in the following Table 1.

                  TABLE 1    ______________________________________                                Metal deposit                       Added    amount           Metal deposition                       amount   (×10.sup.10 atoms/cm.sup.2)           preventive  (wt %)   Al       Fe    ______________________________________    Example 1             EDDHA         0.01     28     <6    Example 2             EDDHA         0.1      27     <6    Example 3             Carmagite     0.1      35     <6    Example 4             Stilbazo      0.1      80     <6    Example 5             PV            0.1      84     <6    Example 6             o,o'-         0.1      89     <6             dihydroxyazobezene    Example 7             Eriochrome Black T                           0.1      110    <6    Example 8             HBED          0.1      120    <6    Comparative             none          0        1800   200    Example 1    Comparative             EDTPO         0.1      330    <6    Example 2    Comparative             Oxalic        0.1      1700   <6    Example 3             bis(salicylidene-             hydrazide)    ______________________________________

EXAMPLES 9 TO 23 (Combination use of A Group and 1 Group) ANDCOMPARATIVE EXAMPLES 4 TO 15

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 0.25:1:5, the mixture solution thus obtainedwas used as the main component for forming an aqueous solvent. To theaqueous solvent thus formed, was added a predetermined amount of atleast 2 specific complexing agents of the present invention disclosed inTable 1 to prepare a surface treatment composition of the presentinvention. Comparative Examples were prepared respectively by adding oneof the complexing agents used in Examples; by adding catechol, Tiron or(catechol+citric acid) disclosed in JP-A-3-219000 as a complexing agent;by adding EDPPO (ethylenediaminetetrakis(methylsulfonic acid)) disclosedin JP-A-5-275405 as a complexing agent; by adding oxalic bis(salicylidenehydrazide) disclosed in JP-A-6-163495 as a complexingagent; or adding no complexing agent. However, it should be noted thatComparative Example 4 is the same as Comparative Example 1; thatComparative Example 5 is the same as Example 1; that Comparative Example6 is the same as Example 2; and that Comparative Example 13 is the sameas Comparative Example 3.

To the surface treatment solutions thus prepared, were added 10 ppb ofeach of Al and Fe (by using chlorides), and a clean silicon wafer (ptype, CZ, plane orientation (100)) was dipped for 10 minutes in each ofthe surface treatment solutions. During dipping, a liquid temperature ofeach surface treatment solution was raised and maintained at 40°-50° C.After dipping, the silicon wafer was overflow-rinsed with ultra-purewater for 10 minutes and was then dried by nitrogen blow to determine Aland Fe deposited on the wafer surface. Al and Fe deposited on the waferwere recovered with a mixture solution of 0.1 wt % of hydrofluoric acidand 1 wt % of hydrogen peroxide, and the metal amounts were measured byflameless atomic absorption spectrometry and were converted into asubstrate surface concentration (atoms/cm²). The results are shown inthe following Table 2.

                  TABLE 2    ______________________________________                                  Metal deposit                                  amount           Metal deposition preventive                                  (×10.sup.10 atoms/    Example           (added amount/wt %)    cm.sup.2)    No.    A Group    B1 Group        Al    Fe    ______________________________________    Example     9     EDDHA (0.01)                      8-xylenol (0.01)                                      <9    <6    10     EDDHA (0.01)                      glycine (0.01)  <9    <6    11     EDDHA (0.01)                      o-phenanthroline (0.01)                                      <9    <6    12     catechol (0.01)                      8-xylenol (0.01)                                      <9    <6    13     Tiron (0.01)                      8-xylenol (0.01)                                      <9    <6    14     Tiron (0.01)                      o-phenanthroline (0.01)                                      <9    <6    15     Tiron (0.01)                      glycine (0.01)  <9    <6    16     Tiron (0.01)                      iminodiacetic acid (0.01)                                      <9    <6    17     Tiron (0.01)                      nitrolotriacetic acid (0.01)                                      <9    <6    18     Tiron (0.01)                      EDTA (0.01)     <9    <6    19     Tiron (0.01)                      ethylenediamine (0.01)                                      40    <6    20     Tiron (0.01)                      triethanolamine (0.01)                                      44    <6    21     Tiron (0.01)                      oxalic bis(salicylidene-                                      <9    <6                      hydrazide) (0.01)    22     Tiron (0.01)                      sodium azide (0.01)                                      44    <6    23     Tiron (0.01)                      acetonitrile (0.01)                                      18    <6    ______________________________________                                Metal deposit                                amount    Example           Metal deposition preventive                                (×10.sup.10 atoms/cm.sup.2)    No.    (added amount/wt %)  Al       Fe    ______________________________________    Compara-    tive    Example    4      none                 1800     200    5      EDDHA (0.01)         28       <6    6      EDDHA (0.1)          27       <6    7      catechol (0.01)      330      <6    8      Tiron (0.01)         300      <6    9      8-xylenol (0.01)     1700     77    10     8-xylenol (0.1)      130      <6    11     o-phenanthroline (0.1)                                1800     40    12     EDTA (0.01)          1700     51    13     EDTPO (0.1)          330      <6    14     oxalic bis(salicylidenehydrazide) (0.1)                                1700     <6    15     catechol (0.01) + citric acid (0.01)                                300      <6    ______________________________________

EXAMPLES 24 TO 28 (Combination use of A Group and B3 Group) andCOMPARATIVE EXAMPLE 16

The same procedure as in Example 9 was repeated, except that complexingagents shown in the following Table 3 were used. The results are shownin the following Table 3.

                  TABLE 3    ______________________________________           Metal deposition preventive                           Metal deposit amount           (added amount/wt %)                           (×10.sup.10 atoms/cm.sup.2)    Example No.             A Group    B2 Group   Al     Fe    ______________________________________    Example    24       EDDHA (0.01)                        HF (0.01)  <9     <6    25       EDDHA (0.01)                        HCl (0.01) <9     <6    26       Tiron (0.01)                        HF (0.01)  35     <6    27       Tiron (0.01)                        HCl (0.01) 35     <6    28       Tiron (0.01)                        benzothiophene                                   71     <6    Comparative             HF (0.1)              1100   1000    Example 16    ______________________________________

EXAMPLES 29 TO 39 (Combination use of A Group and B3 Group)

The same procedure as in Example 9 was repeated, except that complexingagents shown in the following Table 4 were used. The results are shownin the following Table 4.

                  TABLE 4    ______________________________________                                  Metal deposit                                  amount          Metal deposition preventive                                  (×10.sup.10 atoms/    Exam- (added amount/wt %)     cm.sup.2)    ple No.          A Group    B3 Group         Al    Fe    ______________________________________    Exam-    ple    29    EDDHA (0.01)                     isopropyl alcohol (0.01)                                      <9    <6    30    EDDHA (0.01)                     phosphoric acid (0.01)                                      <9    <6    31    Tiron (0.01)                     isopropyl alcohol (0.01)                                      27    <6    32    Tiron (0.01)                     catechol (0.01)  27    <6    33    Tiron (0.01)                     1,4-dioxane (0.01)                                      27    <6    34    Tiron (0.01)                     potassium sulfate (0.01)                                      27    <6    35    Tiron (0.01)                     potassium nitrite (0.01)                                      18    <6    36    Tiron (0.01)                     phosphoric acid (0.01)                                      25    <6    37    Tiron (0.01)                     tripolyphosphoric acid (0.01)                                      70    <6    38    Tiron (0.01)                     perchloric acid (0.01)                                      53    <6    39    Tiron (0.01)                     potassium carbonate (0.01)                                      53    <6    ______________________________________

EXAMPLES 40 TO 44 (Combination use of A Group and B4 Group) andCOMPARATIVE EXAMPLE 17

The same procedure as in Example 9 was repeated, except that complexingagents shown in the following Table 5 were used. The results are shownin the following Table 5.

                  TABLE 5    ______________________________________           Metal deposition preventive                               Metal deposit amount    Example           (added amount/wt %) (×10.sup.10 atoms/cm.sup.2)    No.    A Group    B4 Group     Al     Fe    ______________________________________    Example    40     EDDHA (0.01)                      acetic acid (0.01)                                   <9     <6    41     Tiron (0.01)                      acetic acid (0.01)                                   <9     <6    42     Tiron (0.01)                      oxalic acid (0.01)                                   27     <6    43     Tiron (0.01)                      malonic acid (0.01)                                   27     <6    44     Tiron (0.01)                      oxalic acid (0.05) +                                   <9     <6                      TMAH (0.05)    Compara-           Tiron (0.01) + TMAH (0.01)                               71       <6    tive Ex-    ample 17    ______________________________________

EXAMPLES 45 TO 49 (Combination use of A Group and B5 Group) andCOMPARATIVE EXAMPLES 18 TO 19

The same procedure as in Example 9 was repeated, except that complexingagents shown in the following Table 6 were used. The results are shownin the following Table 6.

                  TABLE 6    ______________________________________                               Metal deposit           Metal deposition preventive                               amount    Example           (added amount/wt %) (×10.sup.10 atoms/cm.sup.2)    No.    A Group    B5 Group     Al     Fe    ______________________________________    Example    45     EDDHA (0.01)                      tartaric acid (0.01)                                   <9     <6    46     catechol (0.01)                      tartaric acid (0.01)                                   50     <6    47     Tiron (0.01)                      tartaric acid (0.01)                                   27     <6    48     Tiron (0.01)                      salicylic acid (0.01)                                   18     <6    49     Tiron (0.01)                      sulfosalicyclic acid                                   27     <6                      (0.01)    Compara-    tive    Example    18     tartaric acid (0.1) 910      190    19     catechol (0.01) + gluconic acid (0.01)                               270      <6    ______________________________________

EXAMPLES 50 TO 51 (Combination use of A2 Group and B6 Group)

The same procedure as in Example 9 was repeated, except that complexingagents shown in the following Table 7 were used. The results are shownin the following Table 7.

                  TABLE 7    ______________________________________                                Metal deposit           Metal deposition preventive                                amount    Example           (added amount/wt %)  (×10.sup.10 atoms/cm.sup.2)    No.    A2 Group    B6 Group     Al     Fe    ______________________________________    50     EDDHA (0.01)                       acetylacetone (0.01)                                    <9     <6    51     Tiron (0.01)                       acetylacetone (0.01)                                    <9     <6    ______________________________________

EXAMPLES 52 TO 57 AND COMPARATIVE EXAMPLES 20 TO 24

100 ppm of EDDHA was added as a metal deposition preventive to a mixtureof aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water in avolume ratio of X:Y:Z to form an aqueous solvent containing the aboveobtained mixture solution as the main component, the temperature ofwhich was raised and maintained at 40°-50° C. to prepare a surfacetreatment composition.

The surface treatment solution thus prepared was allowed to stand for apredetermined time, and 1 ppb of each of Al and Fe (by using chlorides)was added therein and a clean silicon wafer (p type, CZ, planeorientation (100)) was dipped for 10 minutes. The dipped wafer wasoverflow-rinsed with ultra-pure water for 10 minutes and was dried bynitrogen blow to determine Al and Fe deposited on the wafer surface. Aland Fe deposited on the silicon wafer were recovered with a mixturesolution of 0.1 wt % of hydrofluoric acid and 1 wt % of hydrogenperoxide, and the metal amounts were measured by flameless atomicabsorption spectrometry and were converted into a substrate surfaceconcentration (atoms/cm²). The results are shown in the following Table8.

                  TABLE 8    ______________________________________                         Time    Metal deposit    Volume ratio (values in                         allowed amount    parentheses () indicate wt %)                         to      (×10.sup.10 atoms/    NH.sub.4 OH  H.sub.2 O.sub.2                          H.sub.2 O                                 stand cm.sup.2)    X            Y        Z      (min) Al    Fe    ______________________________________    Example 52            0.5(1.2) 1.0(2.5) 11   120   42    <6    Example 53            0.5(1.2)  0.1(0.25)                              11.9 120   32    <6    Example 54             0.2(0.05)                     1.0(2.7) 10   120   24    <6    Example 55            1.0(2.5) 1.0(2.6) 10   120   53    <6    Example 56            0.5(1.3) 1.0(2.7) 10   120   38    <6    Example 57            0.1(0.3) 0.2(0.5) 10   120   12    <6    Comparative            0.5(1.2) 2.0(5.0) 10   0     27    <6    Example 20    Comparative            0.5(1.2) 2.0(5.0) 10   120   180   <6    Example 21    Comparative            0.5(1.2) 2.0(5.0) 10   240   580   52    Example 22    Comparative            0.5(1.2) 12(30)   0    120   850   70    Example 23    Comparative            2.0(4.3) 2.0(4.4) 10   120   690   43    Example 24    ______________________________________

As shown in Table 8, when an oxidizing agent concentration is at most 3wt %, a metal deposition preventive effect on a metal surface ismaintained even after allowing to stand for a long time.

EXAMPLE 58

After allowing to stand for 2 hours, a metal deposition amount on asubstrate was Al˜18, Fe<6 atoms/cm². Thus, a metal deposition preventiveperformance was maintained.

EXAMPLES 59 TO 60 AND COMPARATIVE EXAMPLES 25 TO 26

1,000 ppm of Tiron was added as a metal deposition preventive to amixture of aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) andwater in a volume ratio of X:Y:Z to form an aqueous solvent containingthe above obtained mixture solution as the main component, thetemperature of which was maintained at 40°-50° C. to prepare a surfacetreatment composition.

After allowing the above prepared surface treatment solution to standfor a predetermined time, 1 ppb of each of Al and Fe (by usingchlorides) was added thereto and a clean silicon wafer (p type, CZ,plane orientation (100)) was dipped therein for 10 minutes. The dippedwafer was overflow-rinsed with pure water for 10 minutes, and was thendried by nitrogen blow to determine Al and Fe deposited on the wafersurface. Al and Fe deposited on the silicon wafer were recovered by amixture solution of 0.1 wt % of hydrofluoric acid and 1 wt % of hydrogenperoxide, and the metal amounts were measured by flameless atomicabsorption spectrometry, and were converted into a substrate surfaceconcentration (atoms/cm²). The results are shown in the following Table9.

                  TABLE 9    ______________________________________                         Time    Metal deposit    Volume ratio (values in                         allowed amount    parentheses () indicate wt %)                         to      (×10.sup.10 atoms/    NH.sub.4 OH  H.sub.2 O.sub.2                          H.sub.2 O                                 stand cm.sup.2)    X            Y        Z      (min) Al    Fe    ______________________________________    Example 59             0.2(0.05)                     1.0(2.7) 10   0     70    <6    Example 60             0.2(0.05)                     1.0(2.7) 10   120   80    <6    Comparative            0.5(1.2) 2.0(5.0) 10   0     84    <6    Example 25    Comparative            0.5(1.2) 2.0(5.0) 10   120   520   <6    Example 26    ______________________________________

As shown in Table 9, even if EDDHA as an organic complexing agent wasreplaced by Tiron, when an oxidizing agent concentration was at most 3wt %, a metal deposition preventive effect on a substrate surface wasmaintained even after allowing to stand for a long time.

EXAMPLE 61 TO 62 AND COMPARATIVE EXAMPLES 27 TO 28

10 ppm of EDDHA and 10 ppm of o-phenanthroline were added as metaldeposition preventives to a mixture of aqueous ammonia (30 wt %),hydrogen peroxide (31 wt %) and water in a volume ratio of X:Y:Z to forman aqueous solvent containing the above mixture solution as the maincomponent, the temperature of which was maintained at 40°-50° C. toprepare a surface treatment composition.

After allowing the above prepared surface treatment solution to standfor a predetermined time, 1 ppb of each of Al and Fe (by usingchlorides) was added thereto, and a clean silicon wafer (p type, CZ,plane orientation (100)) was dipped therein for 10 minutes. The dippedwafer was overflow-rinsed with ultra-pure water for 10 minutes and wasthen dried by nitrogen blow to determine Al and Fe deposited on thewafer surface. Al and Fe deposited on the silicon wafer were recoveredby a mixture solution of 0.1 wt % of hydrofluoric acid and 1 wt % ofhydrogen peroxide, and the metal amounts were measured by flamelessatomic absorption spectrometry and were converted into a substratesurface concentration (atoms/cm²). The results are shown in thefollowing Table 10

                  TABLE 10    ______________________________________                         Time    Metal deposit    Volume ratio (values in                         allowed amount    parentheses () indicate wt %)                         to      (×10.sup.10 atoms/    NH.sub.4 OH  H.sub.2 O.sub.2                          H.sub.2 O                                 stand cm.sup.2)    X            Y        Z      (min) Al    Fe    ______________________________________    Example 61             0.2(0.05)                     1.0(2.7) 10   0     <9    <6    Example 62             0.2(0.05)                     1.0(2.7) 10   120   <9    <6    Comparative            0.5(1.2) 2.0(5.0) 10   0     <9    <6    Example 27    Comparative            0.5(1.2) 2.0(5.0) 10   120   220   <6    Example 28    ______________________________________

EXAMPLES 63 TO 64 AND COMPARATIVE EXAMPLE 29

An aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a ratio of 1:1:10, and the mixture solution thus obtained wasused as the main component for forming an aqueous solvent. To theaqueous solvent, was added a predetermined amount of each of complexingagents of the present invention shown in the following Table 11 as ametal deposition preventive to prepare a surface treatment compositionof the present invention. Comparative Example was prepared by adding nocomplexing agent to the aqueous solvent.

A silicon wafer (p type, CZ, plane orientation (100)), the surface ofwhich was contaminated with a metal, was dipped in the above preparedsurface treatment solution for 10 minutes to clean the metalcontamination. During dipping, a liquid temperature of the surfacetreatment solution was raised and maintained at 40°-50° C. Afterdipping, the silicon wafer was overflow-rinsed with ultra-pure water for10 minutes, and was then dried by nitrogen blow to determine a metal onthe wafer surface. The metal on the silicon wafer surface was recoveredwith a mixture solution of 0.1 wt % of hydrofluoric acid and 1 wt % ofhydrogen peroxide, and the metal amount was measured by flameless atomicabsorption spectrometry and was converted into a substrate surfaceconcentration (atoms/cm²). The results are shown in the following Table11.

                  TABLE 11    ______________________________________                            Metal deposit           Metal deposition preventive                            amount           (added amount/wt %)                            (×10.sup.10 atoms/cm.sup.2)    Example No.             A Group    B Group     Al   Fe   Ca    ______________________________________    Before washing             --                 3500   1100 350    Example 63             EDDHA (0.01)                        o-phenanthroline                                    <9   <6   <4                        (0.005)    Example 64             EDDHA (0.01)                        acetic acid (0.05)                                    <9   <6   <4    Comparative             none                   790  990  120    Example 29    ______________________________________

As shown in Table 11, when the substrate is treated with the surfacetreatment solution of the present invention, metal deposition from thesolution onto the substrate surface can be prevented, and metalcontamination can be removed when the substrate surface is contaminatedwith a metal.

EXAMPLE 65 AND COMPARATIVE EXAMPLES 30 TO 32

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, was added a predetermined amount of a complexing agent shownin the following Table 12 as a metal deposition preventive to prepare asurface treatment composition of the present invention. The amount ofthe complexing agent added was expressed by a weight ratio (ppm) to theaqueous solvent. Comparative Example was made without adding acomplexing agent. The total volume of the surface treatment compositionwas 2.8 l and was placed in a quartz tank with no lid having a capacityof 6 l. A temperature of the solution was raised and maintained at40°-50° C.

The surface treatment solution thus prepared was allowed to stand at40°-50° C. for such a predetermined time as shown in the following Table12. When allowing to stand, the ammonia content evaporated was suppliedwith aqueous ammonia (30 wt %) containing a predetermined amount of acomplexing agent shown in the following Table 12. The amount of thecomplexing agent added in this case was expressed by a weight ratio(ppm) to the ammonia aqueous solution. The amount of the ammonia aqueoussolution supplied was 76 ml per hour. After allowing to stand for apredetermined time, 1 ppb of each of Al and Fe was added thereto and aclean silicon wafer (p type, CZ, plane orientation (100)) was dippedtherein for 10 minutes. After dipping, the wafer was overflow-rinsedwith ultra-pure water for 10 minutes, and was then dried by nitrogenblow to determine Al and Fe deposited on the wafer surface. Al and Fedeposited on the silicon wafer were recovered with a mixture solution of0.1 wt % of hydrofluoric acid and 1 wt % of hydrogen peroxide, and metalamounts were measured by flameless atomic absorption spectrometry andwere converted into substrate surface concentrations (atoms/cm²). Theresults are shown in the following Table 12. Further, for comparison,experimental results in cases of not allowing surface treatmentsolutions to stand (case of adding no complexing agent: ComparativeExample 30, case of adding a complexing agent: Comparative Example 31),and experimental results in case of allowing a surface treatmentsolution to stand for 4 hours, during which evaporated ammonia contentwas supplied with aqueous ammonia containing no complexing agent(Comparative Example 32), are shown in the following Table 12.

                  TABLE 12    ______________________________________    Complexing agent               Metal depos-    (added amount/ppm)     Time    it amount    in initial sur-            allowed (×10.sup.10    face treatment in aqueous  to stand                                       atoms/cm.sup.2)    composition    ammonia supplied                               (hr)    Al   Fe    ______________________________________    Example 65            EDDHA (100)                       EDDHA (1200)                                   4     18   <6    Comparative            none       no supplied 0     340  75    Example 30    Comparative            EDDHA (100)                       no supplied 0     18   <6    Example 31    Comparative            EDDHA (100)                       Supplied aqueous                                   4     310  250    Example 32         ammonia contain-                       ing no additive    ______________________________________

As shown in Table 12, when evaporated ammonia content is supplied withaqueous ammonia containing 1,200 ppm of EDDHA, a metal depositionpreventive effect on a substrate surface can be maintained even afterallowing the surface treatment solution to stand for a long time.

EXAMPLES 66 TO 67 AND COMPARATIVE EXAMPLES 33 TO 34

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, were added predetermined amounts of two complexing agentsshown in the following Table 13 as metal deposition preventives toprepare a surface treatment composition of the present invention. Thissolution was maintained at 40°-50° C. and was allowed to stand for 4hours. Thereafter, metal deposition properties on a substrate surfacewere evaluated in the same manner as in Example 65. When allowing tostand, an evaporated ammonia content was supplied with aqueous ammonia(30 wt %) containing predetermined amounts of two complexing agentsshown in Table 13. For comparison, results in case of supplying anevaporated ammonia content with aqueous ammonia containing no complexingagent are shown also in the following Table 13. All other experimentconditions were the same as those in Example 65.

                  TABLE 13    ______________________________________    Complexing agent               Metal depos-    (added amount/ppm)     Time    it amount    in initial sur-            allowed (×10.sup.10    face treatment in aqueous  to stand                                       atoms/cm.sup.2)    composition    ammonia supplied                               (hr)    Al   Fe    ______________________________________    Example 66            EDDHA (20) EDDHA (240) 4     <9   <6            o-phenanthro-                       o-phenanthroline            line (10)  (120)    Example 67            EDDHA (20) EDDHA (240) 4     <9   <6            acetic acid (10)                       acetic acid (120)    Comparative            EDDHA (20) Supplied aqueous                                   4     310  230    Example 33            o-phenanthro-                       ammonia contain-            line (10)  ing no additive    Comparative            EDDHA (20) Supplied aqueous                                   4     380  180    Example 34            acetic acid (10)                       ammonia contain-                       ing no additive    ______________________________________

EXAMPLES 68 TO 71 AND COMPARATIVE EXAMPLES 35 TO 37

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 1:2:100, and to the aqueous solvent thusobtained, were added predetermined amounts of two complexing agentsshown in the following Table 14 as a metal deposition preventive ormetal-removing agent to prepare a surface treatment composition of thepresent invention. This solution was maintained at 35°-45° C., and afterallowing the surface treatment composition to stand for 4 hours or 8hours, metal deposition properties on a substrate surface were evaluatedin the same manner as in Example 65. During allowing to stand, anevaporated ammonia content was supplied with aqueous ammonia (30 wt %)containing predetermined amounts of two complexing agents shown in thefollowing Table 14. The amount of the ammonia aqueous solution suppliedwas 17 ml per hour. For comparison, experimental results in case ofsupplying an evaporated ammonia content with aqueous ammonia containingno complexing agent are shown in the following Table 14. All otherexperimental conditions were the same as those in Example 65.

                  TABLE 14    ______________________________________    Complexing agent               Metal depos-    (added amount/ppm)     Time    it amount    in initial sur-            allowed (×10.sup.10    face treatment in aqueous  to stand                                       atoms/cm.sup.2)    composition    ammonia supplied                               (hr)    Al   Fe    ______________________________________    Example 68            EDDHA (2)  EDDHA (200) 4     <9   <6            o-phenanthro-                       o-phenanthro-            line (1)   line (100)    Example 69            EDDHA (2)  EDDHA (200) 8     <9   <6            o-phenanthro-                       o-phenanthro-            line (1)   line (100)    Example 70            EDDHA (2)  EDDHA (200) 4     <9   <6            acetic acid (1)                       acetic acid                       (100)    Example 71            Tiron (50) Tiron (5000)                                   4     <9   <6            o-phenanthro-                       o-phenanthro-            line (5)   line (500)    Comparative            EDDHA (2)  Supplied aqueous                                   4     76   18    Example 35            o-phenanthro-                       ammonia contain-            line (1)   ing no additive    Comparative            EDDHA (2)  Supplied aqueous                                   4     90   25    Example 36            acetic acid (1)                       ammonia contain-                       ing no additive    Comparative            Tiron (50) Supplied aqueous                                   4     120  45    Example 37            o-phenanthro-                       ammonia contain-            line (5)   ing no additive    ______________________________________

EXAMPLE 72 AND COMPARATIVE EXAMPLE 38

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 1:2:100, and to the aqueous solvent thusobtained, were added predetermined amounts of two complexing agentsshown in the following Table 15 as a metal deposition preventive ormetal-removing agent to prepare a surface treatment composition of thepresent invention. This solution was maintained at 60°-70° C., and afterallowing the solution to stand for 4 hours, metal deposition propertieson a substrate surface were evaluated in the same manner as in Example63. During allowing to stand, an evaluated ammonia content was suppliedwith aqueous ammonia (30 wt %) containing predetermined amounts of twocomplexing agents shown in the following Table 15. The amount of theaqueous ammonia supplied was 32 ml per hour. For comparison,experimental results in case of supplying an evaporated ammonia contentwith aqueous ammonia containing no complexing agent are shown in thefollowing Table 15. All other experimental conditions were the same asthose in Example 65.

                  TABLE 15    ______________________________________    Complexing agent               Metal depos-    (added amount/ppm)     Time    it amount    in initial sur-            allowed (×10.sup.10    face treatment in aqueous  to stand                                       atoms/cm.sup.2)    composition    ammonia supplied                               (hr)    Al   Fe    ______________________________________    Example 72            EDDHA (2)  EDDHA (200) 4     <9   <6            o-phenanthro-                       o-phenanthro-            line (1)   line (100)    Comparative            EDDHA (2)  Supplied aqueous                                   4     180  92    Example 38            o-phenanthro-                       ammonia contain-            line (1)   ing no additive    ______________________________________

EXAMPLE 73 AND COMPARATIVE EXAMPLES 39 TO 40

7 wt % of nitric acid aqueous solution was added to commerciallyavailable EDDHA (CATALOG #: E4135, Lot No. 85H5041 manufactured by SIGMACHEMICAL COMPANY, USA) in an amount of 10 ml per g of EDDHA to solveEDDHA. The EDDHA nitric acid aqueous solution was filtrated by a Teflonfilter (PTFE made) having an opening diameter of 0.1 μm to removeinsoluble impurities. To the filtrate thus obtained, was added 6 wt % ofammonia aqueous solution until a pH value of the solution becomes 8,thereby precipitating a crystal of EDDHA. The EDDHA crystal was obtainedby filtrating with a filter having an opening diameter of 5 μm. Further,the crystal thus obtained was washed with pure water on the filter.

The above operation was repeated 8 times, and the EDDHA crystal thuspurified was dried in a drier to obtain a highly pure EDDHA of thepresent invention.

A metal impurity amount in the EDDHA was analyzed after beingwet-decomposed in the following manner. 1 g of EDDHA was placed in aclean quartz flask, and was subjected to carbonization by heat afteradding 5 ml of sulfuric acid. Thereafter, nitric acid and aqueoushydrogen peroxide were added thereto, and the resultant EDDHA wassubjected to oxydation-decomposition while heating. The resultant EDDHAwas further heated to evaporate materials other than sulfuric acid, andwas adjusted to 50 ml with pure water. In this manner, the sample waswet-decomposed, and the metal impurity amount was analyzed by ICP-AESmethod and atomic absorption spectrometry.

Analytical values of the highly pure EDDHA obtained in the aboveoperation are shown in the following Table 16. Also, for comparison,analytical values of unpurified EDDHA (Lot NO. 85H5041: ComparativeExample 39, Lot No. 117F50221: Comparative Example 40, manufactured bySIGMA CHEMICAL COMPANY, USA) are shown in the following Table 16.

                  TABLE 16    ______________________________________                       Conventional product             Highly pure                       (unpurified product)                   product     Comparative                                       Comparative    Element Unit   Example 73  Example 39                                       Example 40    ______________________________________    Al      ppm    <5          11      6    Cr      ppm    <1          50      4.5    Cu      ppm    <1          4       4    Fe      ppm    <1          950     210    Mn      ppm    <0.25       60      4    Na      ppm    <0.5        1500    120    Ni      ppm    <2.5        80      4    Zn      ppm    <1          7.5     19    ______________________________________

As shown in Table 16, conventionally commercially available EDDHAcontains metal impurities respectively in an amount of several toseveral thousands ppm, but the metal impurities can be reduced to atmost 5 ppm by the purification method of the present invention.

EXAMPLE 74

To commercially available EDDHA (CATALOG #: E4135, Lot No. 117F50221:Comparative Example 40, manufactured by SIGMA CHEMICAL COMPANY, USA),was added 3 wt % of ammonia aqueous solution in an amount of 10 ml per gof EDDHA to dissolve EDDHA. This EDDHA nitric acid aqueous solution wasfiltrated by a Teflon filter (PTFE made) having an opening diameter of0.1 μm to remove insoluble impurities. To the filtrate thus obtained,was added 23 wt % of nitric acid aqueous solution until a pH value ofthe solution becomes 6, thereby precipitating EDDHA crystal. The EDDHAcrystal was obtained by filtrating with a Teflon filter (PTFE made)having an opening diameter of 5 μm. Further, the crystal thus obtainedwas washed with pure water on the filter.

The above operation was repeated 7 times, and the purified EDDHA crystalwas dried in a drier to obtain highly pure EDDHA of the presentinvention. The highly pure EDDHA of the present invention was analyzedin the same manner as in Example 73, and the results are shown in thefollowing Table 17.

                  TABLE 17    ______________________________________                        Highly pure    Element      Unit   product Example 74    ______________________________________    Al           ppm    <5    Cr           ppm    <1    Cu           ppm    <1    Fe           ppm    <1    Mn           ppm    <0.25    Na           ppm    <0.5    Ni           ppm    <2.5    Zn           ppm    <1    ______________________________________

EXAMPLE 75

240 ppm of the highly pure EDDHA obtained in Example 74 was added anddissolved in a highly pure ammonia aqueous solution (30 wt %) to obtainEDDHA-added ammonia aqueous solution of the present invention.Analytical results of metal impurities in the EDDHA-added ammoniaaqueous solution thus obtained are shown in the following Table 18.

                  TABLE 18    ______________________________________    Element        Unit   Example 75    ______________________________________    Al             ppb    <1    Cr             ppb    <0.5    Cu             ppb    <0.5    Fe             ppb    <0.5    Mn             ppb    <0.5    Na             ppb    <0.5    Ni             ppb    <0.5    Zn             ppb    <0.5    ______________________________________

As shown in Table 18, each of metal element contents can be reduced toat most 1 ppb by using the highly pure EDDHA of the present invention(in case that an amount of EDDHA added is 240 ppm).

EXAMPLES 76 TO 77 AND COMPARATIVE EXAMPLES 41 TO 44

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, was added a predetermined amount of EDDHA shown in thefollowing Table 19 to prepare a surface treatment composition of thepresent invention. The highly pure EDDHA obtained in Example 71 was usedas EDDHA. Also, for comparison, conventionally commercially availableEDDHA (CATALOG #: E4135, Lot No. 117F50221: the same as used inComparative Example 40, manufactured by SIGMA CHEMICAL COMPANY, USA) wasused as it is for Comparative Examples. Amounts of EDDHA added wereexpressed by weight ratio (ppm) to the aqueous solvent. Further, forcomparison, a comparative composition containing no EDDRA in the aqueoussolvent was prepared. The total volume amount of a surface treatmentcomposition was 2.8 l, and the composition was placed in a quartz tankwith no lid having a capacity of 6 l. A temperature of the liquid wasraised and maintained at 55°-65° C.

The surface treatment solution thus prepared was allowed to stand at55°-65° C. for a predetermined time. After allowing to stand for apredetermined time, 1 ppb of each of Al and Fe was added thereto, and aclean silicon wafer (p type, CZ, plane orientation (100)) was dippedtherein for 10 minutes. After dipping, the wafer was overflow-rinsedwith ultra-pure water for 10 minutes, and was then dried by nitrogenblow to determine Al and Fe deposited on the wafer surface. Al and Fedeposited on the silicon wafer were recovered by a mixture solution of0.1 wt % of hydrofluoric acid and 1 wt % of hydrogen peroxide, and themetal amounts were measured by flameless atomic absorption spectrometryand were converted into substrate surface concentrations (atoms/cm²).The results are shown in the following Table 19. Further, forcomparison, experimental results in cases of not allowing surfacetreatment solutions to stand are shown in the following Table 19.

                  TABLE 19    ______________________________________                        Time    Metal deposit                        allowed amount    Complexing agent    to stand                                (×10.sup.10 atoms/cm.sup.2)    (added amount/ppm)  (hr)    Al       Fe    ______________________________________    Example 76            highly pure EDDHA (100)                            0       25     <6    Example 77            highly pure EDDHA (100)                            2       50     <6    Comparative            conventional EDDHA (100)                            0       25     <6    Example 41    Comparative            conventional EDDHA (100)                            2       380    450    Example 42    Comparative            none            0       340    85    Example 43    Comparative            none            2       350    80    Example 44    ______________________________________

As shown in Table 19, when the highly pure EDDHA was used, a metaldeposition preventive effect on a substrate surface was maintained evenafter a surface treatment solution was allowed to stand at 60° C. for along time. On the other hand, when conventional EDDHA was used, adeposition preventive effect could be recognized immediately afteraddition, but the effect was lowered while using for a long time.Particularly, a deposition amount of Fe was more increased than in thecase of using no complexing agent. This is probably because a largeamount of Fe contained in the conventional EDDHA was separated fromEDDHA at the decomposition of EDDHA and was deposited on the substratesurface.

EXAMPLES 78 TO 80 AND COMPARATIVE EXAMPLES 45 TO 46

Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and water weremixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, was added predetermined amounts of two complexing agents shownin the following Table 20 as metal deposition preventives to prepare asurface treatment composition of the present invention. The highly pureEDDHA obtained in Example 73 was used as EDDHA. For comparison,conventional EDDHA (CATALOG #: E4135, Lot No. 117F50221: the same asused in Comparative Example 40, manufactured by SIGMA CHEMICAL COMPANY,USA) was used for Comparative Examples. An amount of each metal elementin acetic acid and o-phenanthroline was at most 1 ppm. This solution wasallowed to stand at 55°-65° C. for a predetermined time, and metaldeposition properties on a substrate surface were evaluated in the samemanner as in Example 73. All other experimental conditions were the sameas those of Example 76. Experimental results are shown in the followingTable 20.

                  TABLE 20    ______________________________________                        Time    Metal deposit                        allowed amount    Complexing agent    to stand                                (×10.sup.10 atoms/cm.sup.2)    (added amount/ppm)  (hr)    Al       Fe    ______________________________________    Example 78            highly pure EDDHA (20)                            0       <9     <6            acetic acid (100)    Example 79            highly pure EDDHA (20)                            2       32     <6            acetic acid (100)    Example 80            highly pure EDDHA (20)                            2       40     <6            o-phenanthroline (10)    Comparative            conventional EDDHA (20)                            0       <9     <6    Example 45            acetic acid (100)    Comparative            conventional EDDHA (20)                            2       329    227    Example 46            acetic acid (100)    ______________________________________

INDUSTRIAL APPLICABILITY

The surface treatment composition of the present invention containing aspecific complexing agent as a metal deposition preventive, prevents asubstrate surface from being contaminated with metal impurities such asAl and Fe from the surface treatment composition, and stably provides anextremely clean substrate surface.

Particularly, when the present invention is applied to alkali cleaningof a semiconductor substrate represented by "ammonia+hydrogenperoxide+water" cleaning, a conventional problem of this cleaning methodconcerning a metal impurity deposition problem is solved, and a highlyclean substrate surface can be provided by this cleaning without beingcontaminated with particles, organic materials and metals. Thus,conventionally employed acid cleaning such as "hydrochloricacid+hydrogen peroxide+water" cleaning conducted after this cleaning canbe omitted, and it is therefore possible to largely reduce the cleaningcost, a clean room cost including an exhauster equipment and the like,thus being largely advantageous in industrial production ofsemiconductor integrated circuits.

We claim:
 1. A method for treating the surface of a substrate whichcomprises (1) applying to the surface a composition comprising a liquidmedium and, at least one complexing agent selected from the groupconsisting of ethylenediaminediorthohydroxyphenylacetic acid,2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonic acid,diammonium 4,4'-bis(3,4-dihyroxyphenylazo)-2,2'-stilbenedisulfonate,Pryrocatechol Violet, o,o'-dihyroxyazobenzene,1,2-dihydroxy-5-nitro-1,2'-azonaphthalene-4-sulfonic acid andN,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, as a metaldeposition preventive in the liquid medium, and (2) etching, polishingor coating the surface of the substrate.
 2. The method according toclaim 1 wherein the liquid medium contains ammonia.
 3. The methodaccording to claim 1, wherein the complexing agent isethylenediaminediorthohydroxyphenylacetic acid.
 4. The method accordingto claim 3 wherein the liquid medium contains ammonia.
 5. The methodaccording to claim 1, wherein the content of the complexing agent issufficient to minimize the deposition of a metal impurity, and rangesfrom 10⁻⁷ to 2 wt. %.
 6. The method according to claim 5 wherein theliquid medium contains ammonia.
 7. The method according to claim 1,wherein the liquid medium is an alkaline aqueous solution.
 8. The methodaccording to claim 1, wherein the alkaline aqueous solution containsammonia and hydrogen peroxide.